In the past it has been difficult to determine the location of a break in a conductor that is located within a cable that has a multiple number of conductors therein. One such means of detecting the location for such a break was by visual inspection. However such a method is not reliable when the break or discontinuity is hidden from view.
A probe that can detect an open, a break or an unused pin in a multiconductor cable is known in the art. The probe operates based on the amount of capacitance between the conductor and the cable. However, the probe cannot precisely determine the location of a break in a conductor of the cable since the probe does not have a timing means.
The present invention is an improvement in the art of detecting the location of a break in a conductor of a multiconductor cable. In the present invention the amount of capacitance between the conductor under investigation and adjacent conductors, is determined by means of a timer. The smaller the capacitance is, between the broken conductor and adjacent conductors, the closer the break is to the automatic cable tester.
In the invention the method measures the charging rate of the capacitance between the conductor under investigation with respect to the other conductors of the cable which are held at ground potential. The charging rate of the capacitance is the result of a charging current into the conductor under test.
A capacitance exists between adjacent conductors of such a cable. The capacitance charging rate between the conductor under investigation and adjacent conductors will depend upon the length of unbroken portion of the conductor under investigation. The longer the unbroken portion of the conductor is from the point of contact with an automatic cable tester, the slower is the charge rate to reach a full charge potential. If the break is near the point of contact with the automatic cable tester, the charge rate is relatively large, whereas if the break is more distance from the point of contact of the automatic cable tester, the charge rate is relatively small.
The time that it takes for the charging current to decrease to a value, such as 1/e of its initial value, is measured in order to detect the location of a break. Alternatively, the time that it takes for the charging voltage buildup to increase to a value, such as (1-1/e) of the value of the applied voltage, can be measured in order to detect the location of a break.